#audio_btn {
  position: absolute;
  right: 20px;
  top: 20px;
  z-index: 200;
  width: 30px;
  height: 30px
}
.off {
  background-size: contain
}
.rotate {
  -webkit-animation: rotating 1.2s linear infinite;
  -moz-animation: rotating 1.2s linear infinite;
  -o-animation: rotating 1.2s linear infinite;
  animation: rotating 1.2s linear infinite
}
@-webkit-keyframes rotating {
  from {
    -webkit-transform: rotate(0)
  }
  to {
    -webkit-transform: rotate(360deg)
  }
}